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"""``HDFDataSet`` loads/saves data from/to a hdf file using an underlying
filesystem (e.g.: local, S3, GCS). It uses pandas.HDFStore to handle the hdf file.
"""
from copy import deepcopy
from pathlib import PurePosixPath
from threading import Lock
from typing import Any, Dict

import fsspec
import pandas as pd

from kedro.io.core import (
    AbstractVersionedDataSet,
    DataSetError,
    Version,
    get_filepath_str,
    get_protocol_and_path,
)

HDFSTORE_DRIVER = "H5FD_CORE"


class HDFDataSet(AbstractVersionedDataSet):
    """``HDFDataSet`` loads/saves data from/to a hdf file using an underlying
    filesystem (e.g. local, S3, GCS). It uses pandas.HDFStore to handle the hdf file.

    Example:
    ::

        >>> from kedro.extras.datasets.pandas import HDFDataSet
        >>> import pandas as pd
        >>>
        >>> data = pd.DataFrame({'col1': [1, 2], 'col2': [4, 5],
        >>>                      'col3': [5, 6]})
        >>>
        >>> # data_set = HDFDataSet(filepath="gcs://bucket/test.hdf", key='data')
        >>> data_set = HDFDataSet(filepath="test.h5", key='data')
        >>> data_set.save(data)
        >>> reloaded = data_set.load()
        >>> assert data.equals(reloaded)

    """

    # _lock is a class attribute that will be shared across all the instances.
    # It is used to make dataset safe for threads.
    _lock = Lock()
    DEFAULT_LOAD_ARGS = {}  # type: Dict[str, Any]
    DEFAULT_SAVE_ARGS = {}  # type: Dict[str, Any]

    # pylint: disable=too-many-arguments
    def __init__(
        self,
        filepath: str,
        key: str,
        load_args: Dict[str, Any] = None,
        save_args: Dict[str, Any] = None,
        version: Version = None,
        credentials: Dict[str, Any] = None,
        fs_args: Dict[str, Any] = None,
    ) -> None:
        """Creates a new instance of ``HDFDataSet`` pointing to a concrete hdf file
        on a specific filesystem.

        Args:
            filepath: Filepath to a hdf file prefixed with a protocol like `s3://`.
                If prefix is not provided, `file` protocol (local filesystem) will be used.
                The prefix should be any protocol supported by ``fsspec``.
                Note: `http(s)` doesn't support versioning.
            key: Identifier to the group in the HDF store.
            load_args: PyTables options for loading hdf files.
                You can find all available arguments at:
                https://www.pytables.org/usersguide/libref/top_level.html#tables.open_file
                All defaults are preserved.
            save_args: PyTables options for saving hdf files.
                You can find all available arguments at:
                https://www.pytables.org/usersguide/libref/top_level.html#tables.open_file
                All defaults are preserved.
            version: If specified, should be an instance of
                ``kedro.io.core.Version``. If its ``load`` attribute is
                None, the latest version will be loaded. If its ``save``
                attribute is None, save version will be autogenerated.
            credentials: Credentials required to get access to the underlying filesystem.
                E.g. for ``GCSFileSystem`` it should look like `{"token": None}`.
            fs_args: Extra arguments to pass into underlying filesystem class constructor
                (e.g. `{"project": "my-project"}` for ``GCSFileSystem``), as well as
                to pass to the filesystem's `open` method through nested keys
                `open_args_load` and `open_args_save`.
                Here you can find all available arguments for `open`:
                https://filesystem-spec.readthedocs.io/en/latest/api.html#fsspec.spec.AbstractFileSystem.open
                All defaults are preserved, except `mode`, which is set `wb` when saving.
        """
        _fs_args = deepcopy(fs_args) or {}
        _fs_open_args_load = _fs_args.pop("open_args_load", {})
        _fs_open_args_save = _fs_args.pop("open_args_save", {})
        _credentials = deepcopy(credentials) or {}

        protocol, path = get_protocol_and_path(filepath, version)

        self._protocol = protocol
        self._fs = fsspec.filesystem(self._protocol, **_credentials, **_fs_args)

        super().__init__(
            filepath=PurePosixPath(path),
            version=version,
            exists_function=self._fs.exists,
            glob_function=self._fs.glob,
        )

        self._key = key

        # Handle default load and save arguments
        self._load_args = deepcopy(self.DEFAULT_LOAD_ARGS)
        if load_args is not None:
            self._load_args.update(load_args)
        self._save_args = deepcopy(self.DEFAULT_SAVE_ARGS)
        if save_args is not None:
            self._save_args.update(save_args)

        _fs_open_args_save.setdefault("mode", "wb")
        self._fs_open_args_load = _fs_open_args_load
        self._fs_open_args_save = _fs_open_args_save

    def _describe(self) -> Dict[str, Any]:
        return dict(
            filepath=self._filepath,
            key=self._key,
            protocol=self._protocol,
            load_args=self._load_args,
            save_args=self._save_args,
            version=self._version,
        )

    def _load(self) -> pd.DataFrame:
        load_path = get_filepath_str(self._get_load_path(), self._protocol)

        with self._fs.open(load_path, **self._fs_open_args_load) as fs_file:
            binary_data = fs_file.read()

        with HDFDataSet._lock:
            # Set driver_core_backing_store to False to disable saving
            # contents of the in-memory h5file to disk
            with pd.HDFStore(
                "in-memory-load-file",
                mode="r",
                driver=HDFSTORE_DRIVER,
                driver_core_backing_store=0,
                driver_core_image=binary_data,
                **self._load_args,
            ) as store:
                return store[self._key]

    def _save(self, data: pd.DataFrame) -> None:
        save_path = get_filepath_str(self._get_save_path(), self._protocol)

        with HDFDataSet._lock:
            with pd.HDFStore(
                "in-memory-save-file",
                mode="w",
                driver=HDFSTORE_DRIVER,
                driver_core_backing_store=0,
                **self._save_args,
            ) as store:
                store.put(self._key, data, format="table")
                # pylint: disable=protected-access
                binary_data = store._handle.get_file_image()

        with self._fs.open(save_path, **self._fs_open_args_save) as fs_file:
            fs_file.write(binary_data)

        self._invalidate_cache()

    def _exists(self) -> bool:
        try:
            load_path = get_filepath_str(self._get_load_path(), self._protocol)
        except DataSetError:
            return False

        return self._fs.exists(load_path)

    def _release(self) -> None:
        super()._release()
        self._invalidate_cache()

    def _invalidate_cache(self) -> None:
        """Invalidate underlying filesystem caches."""
        filepath = get_filepath_str(self._filepath, self._protocol)
        self._fs.invalidate_cache(filepath)
